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California has two-thirds of the nation's earthquake risk. Some 15,700 known faults crisscross the state, and more than 500 are considered active. Certain structures that lack adequate bolting and bracing are more vulnerable to earthquake damage. Older houses are often not bolted to their foundations and lack bracing on the wood framed exterior walls enclosing the crawl space. Houses without adequate bolting and bracing are prone to sliding or toppling off their foundation during an earthquake. This type of serious damage can be prevented with proper seismic retrofit of the crawl space.
Interactive hazard maps are available from the California Governor's Office of Emergency Services ("Cal OES") on its 'My Hazards Awareness Map' website. Go to http://myhazards.caloes.ca.gov and click on the Earthquake tab. This website provides general information on earthquake hazards. By entering your address into the map search field at the top of the page and hitting 'Map Search,' a screen will appear with your address located on a map showing your local earthquake hazard. The page will also include a written description of earthquake hazards in your area.
There is no such thing as an earthquake-proof structure. There are measures that can be taken that will likely reduce the potential for or severity of earthquake damage. The California Existing Building Code states that the retrofit provisions of the code are "minimum standards intended to improve the seismic performance of residential buildings; however, they will not necessarily prevent earthquake damage."
The adoption of Chapter A3 into the California Building Code provided the first uniform guidelines for a quality, science-based retrofit for existing houses. It was the result of extensive engineering to provide prescriptive standards for seismic strengthening of cripple walls and sill plate anchorage of light, wood-framed houses. For qualifying houses that sit directly on their raised foundation or have cripple walls that are 4 feet tall or less, Chapter A3 that can be used without a site-specific engineering retrofit design, which means it is pre-engineered so contracting with an engineer to draw plans is not required. Chapter A3 allows an engineered solution to be used for houses with cripple walls that exceed 4 feet tall. Plan Set A and the LA Standard Plan Set are based on Chapter A3 and are considered to be an appropriate construction documents for the code.
The prescriptive provision or plan set is a "blueprint" version of a prescriptive ("cookbook") standard for strengthening homes to better withstand earthquake shaking. When approved by the local building official, the plan set may be used to strengthen older homes without the need for costly site-specific plans and design calculations. This plan set provides a low-cost method to help improve an older home's chances of surviving an earthquake. Standard Plan Set A and LA Standard Plan set are examples of prescriptive standards.
A cripple wall is a less-than-full-heights wall between the house foundation and the base of the first floor of the house.
After the 1989 Loma Prieta and the 1994 Northridge earthquakes, there was a push in California to get cripple wall homes retrofitted. There was a building code for new construction but there wasn’t any guideline or standard for the retrofit of an existing home with a cripple wall vulnerability. At that time a homeowner could hire an engineer to design a retrofit specifically for their home but there was no consensus document on the best way to mitigate the cripple wall vulnerability.
There were also a growing number of construction companies that marketed seismic retrofits but, , once again, these companies were not providing retrofits designed to any statewide standard.
In the late 1990s studies were performed in Northern and Southern California that found around 80% of cripple wall retrofits were not done properly. To remedy this serious issue the LA building department and a committee in Northern California, the Association of Bay Area Governments (ABAG), created “plan sets” that would provide complete and effective standards for cripple wall retrofits (i.e. The LADBS Standard Plan #1 and Standard Plan Set A). The Association of Bay Area Governments (ABAG) website identifies the Northern California committee members as representatives from the East Bay, Peninsula, and Monterey Bay chapters of the International Code Council (ICC), along with representatives from the Association of Bay Area Governments (ABAG) Earthquake Program, the Structural Engineers Association of Northern California (SEAONC) Existing Buildings, Seismology and Structural Standards Committees, the California Building Officials (CALBO) Seismic Safety and Emergency Preparedness Committees, the Earthquake Engineering Research Institute (EERI) Northern California Chapter, and building contractors specializing in home retrofit. In order to promote affordable retrofits Plan Set A and LADBS Standard Plan #1 were designed as prescriptive retrofit standards that could be used by owner-builders or contractors without an individual engineered retrofit plan.
In 2011 the State of California adopted Chapter A3 into the California Existing Building Code. Chapter A3 is a prescriptive seismic retrofit of the sill plate anchorage and cripple wall bracing vulnerability. Both Plan Set A and the LA Standard Plan Set #1 are considered to be construction documents that are in conformance with Chapter A3.
The Earthquake Brace and Bolt Program requires that retrofits be in accordance with Chapter A3 in order to qualify for the financial incentive of up to $3,000. To simplify the permitting process the EBB program also allows the use of Plan Set A or the LA Standard Plan Set #1 as construction documents.
Plan Set A/LADBS Standard Plan #1 vs a “designed” retrofit:
In order to cover the variations in houses, seismic hazard, and provide a margin of safety, Plan Set A/LADBS Standard Plan #1 are slightly more conservative than Chapter A3. Consequently, it may be possible to have an engineered design that specifies fewer anchor bolts or foundation anchors and less plywood sheathing. However, the cost of the engineering design would likely exceed the cost savings.
Please note that an engineered design must be completed by a civil or structural engineer registered in California or a licensed architect. A contractor is not legally qualified to design a retrofit. Also note that a permit is required throughout California for the seismic retrofit work. The EBB program does accept engineered and permitted retrofits provided they meet these legal standards and other program requirements.
A building site with a natural slope of 10 percent or less, if a house is supported by columns or beams, it's likely that the house is on a slope greater than 10 percent.
The framing of the first floor of the house is composed of beams and cross-breams made of wood. You should be able to see this by looking under the house to see if the first floor is supported by wood framing.
A continuous perimeter foundation is typically concrete and continuous under the exterior walls of a dwelling. Partial perimeter foundations or unreinforced masonry need to be evaluated by a design professional.
A slab-on-grade foundation means no basement and no basement wall – just one slab of concrete on which your house is constructed.
Typical San Francisco single-family row houses (often referred to as soft-story structures) do not qualify for an EBB retrofit without an engineered design because of two conditions:
The EBB program relies on adherence to the California Building Code, Appendix Chapter A3. This requires that retrofits be completed with a permit, signed by your local enforcing agency (building official), that states the work was completed in accordance with the California Building Code, Appendix Chapter A3. Chapter A3 sets prescriptive standards for strengthening that may be approved by the building official without requiring plans or calculations prepared by a registered design professional (architect or engineer).
In order to use the prescriptive standards in Chapter A3 without plans prepared by an engineer the house must meet certain requirements that include:
The prescriptive provisions in A3 also require that the house has a minimum amount of wall at each of the perimeter bearing walls that can be sheathed with plywood (or OSB). These minimums vary depending on the number of stories of the house. They are summarized in the table below:
As an example, a one-story house with wood or asphalt shingles and exterior wood siding the cripple walls must have at least one sheathed wall at each end and the total length of sheathed wall must be at least 40% of the total length of the wall. For a forty foot wall with a large garage door opening, Chapter A3 requires one 8 foot long wall either side of door opening. This number increases to 50% for a two-story house and to 80% for a three story house (Two 10 foot walls either side of the garage door). These values increase if the house has more than one story and heavy roofing or exterior finishes.
1. Cripple wall - A less than full height wood stud wall extending from the top of the foundation to the underside of the lowest floor framing
Ground shaking is the primary cause of earthquake damage to man-made structures. When the ground shakes strongly, buildings can be damaged or destroyed. The influence of the soil on earthquake induced ground shaking at a building site is called the site effect. For example, this site effect was evident during the 1989 Loma Prieta earthquake, when areas of the Bay Area with soft soils experienced stronger shaking than other areas at comparable distance from the source.
In addition to the site effect, other factors influence the strength of earthquake shaking at a site including the earthquake’s magnitude and the site’s proximity to the fault. Consequently, a house on bedrock can still experience damaging ground shaking in a large nearby earthquake. This means that Bay Area houses on bedrock that experienced little or no ground shaking in the Loma Prieta earthquake could experience very strong, damaging shaking in a large earthquake on the nearby Hayward fault.
Older houses on soft soil or bedrock should be assessed for adequate sill plate anchorage and cripple wall bracing and retrofitted, if necessary.
Earthquake retrofits and earthquake insurance both have clear benefits and are not mutually exclusive of each other. Earthquake retrofitting is recommended to mitigate known seismic vulnerabilities in structures but it does not “earthquake proof” a house. Seismic retrofits address known weakness such as inadequate sill plate anchorage or cripple wall bracing that can cause expensive, disruptive, and even dangerous damage during an earthquake.
However, retrofits do not eliminate the possibility of damage particularly to unreinforced masonry chimneys, finishes, and building contents. Even new houses built to current codes were not designed to be damage-free after an earthquake. In California, your residential insurance policy doesn’t cover your home or your belongings against earthquakes. If you don’t have earthquake insurance, you’re not covered for earthquake damage or any additional costs needed to live elsewhere while your home is being repaired or rebuilt.
We recommend homeowners consider the physical and financial protection offered by retrofitting and insurance.
The goal of the Brace + Bolt programs is to provide incentive grants to homeowners who strength their houses with a Chapter A3 seismic retrofit. Currently there are three Brace + Bolt programs:
While the goal is the same for all three programs, the requirements are not. To help you understand the requirements for payment for the program you are in, here is the Brace + Bolt Programs Quick Reference Guide.
The Earthquake Brace + Bolt program was created by the California Residential Mitigation Program (“CRMP”). Earthquake Brace + Bolt offers up to $3,000 for homeowners to seismically retrofit their houses. To be considered for participation in the program once registration opens, homeowners must complete the qualification questionnaire located on the website at www.earthquakebracebolt.com .
We do not have a schedule of planned expansions, but program locations and ZIP Codes will be posted on the website. To receive updates about the program, please sign up for the mailing list.
The cost of a retrofit depends on the size of the cripple wall (height, length, width) and the cost of materials and labor. The cost also depends on whether there is any damage or rot in the existing wood-frame members of the house or if the foundation needs repair. The average statewide program cost for a retrofit is about $5,500.
No, CRMP is a joint powers authority formed by the California Earthquake Authority (CEA) and the Governor's Office of Emergency Services (Cal OES) through a Joint Exercise of Powers Agreement (JPA). CRMP is a separate legal entity, and it is not a state agency.
The program is presently funded with contributions from the California Earthquake Authority's Mitigation Fund. The program is funded with contributions from the California Earthquake Authority's Loss Mitigation Fund and with money from the FEMA Hazard Mitigation Grant Program (HMGP).
EBB ZIP Codes are selected using the protocol criteria approved by the CRMP Governing Board. All California ZIP Codes were ordered by the following two criteria which were weighted equally.
1. Earthquake Hazard: Hazard was identified using the United States Geological Survey (USGS) earthquake hazard map for California.
2. Earthquake Vulnerability: Vulnerability was represented by identifying the percentage of pre-1979 houses in ZIP Codes in California (US Census Data). Older houses are more likely to require earthquake bracing and bolting.
EBB is expanding ZIP Code coverage each year. In 2015, we were in the 26 highest-ranking California ZIP codes based on the protocols. In 2018, we expanded to more than 180 of the highest-ranking California ZIP codes based on the protocols. Over time we hope to get to all high hazard areas in the state with additional funding from a variety of sources.
No. EBB does not cover any work done on chimneys; however, you may find some helpful information in this document from FEMA, which addresses how to repair damaged chimneys and what to do to minimize future damage and risk.
When registration is open, complete the questionnaire located on the website to see if your house qualifies for the program. Those who successfully pass the qualification questions can then apply to participate.
Once registration is closed, a random drawing will be held to select registrants to participate in the program. Homeowners will be notified after registration has closed.
Homeowners will be notified by email (by mail or phone for paper applications) if they are selected to participate in the program. Notices will be sent when the selection process has been completed.
Houses that meet the requirements of the program are those that satisfy the requirements of the 2010 California Existing Building Code, Appendix Chapter A3 (Chapter A3).
Houses that typically meet, but are not guaranteed to meet, the requirements of the program are:
Owners of buildings of four or fewer units and who rent some of the units (one unit must be owner-occupied), with a raised foundation and a cripple wall of four feet or less, may be eligible for the program. The local building official has final say as to which structures qualify for retrofit using Chapter A3 and the standard plan sets (Plan Set A and the Los Angeles Standard Plan Set). Check with your local building official before starting the retrofit project.
This program offers incentives to homeowners who have not yet completed a seismic retrofit. Retrofitting work done previously is not eligible for this program.
EBB is not currently requiring initial inspections for the program. To find out if your house qualifies you can contact one of the contractors on the Contractor Directory. The contractors on the list have taken the FEMA training for seismic rehabilitation of single family dwellings. Contractors typically provide this service for free as part of an estimate for the project.
Homeowners who complete all the necessary work and turn in all required documentation will receive a check of up to $3,000 to pay covered expenses.
Anything over $3,000 is the responsibility of the homeowner.
EBB will fund actual expenses, as allowed under the program, up to $3,000. If the retrofit costs $1,500 to complete, then the program will fund up to $1,500 for actual expenses, as allowed under the program.
In order to qualify for the incentive you must submit the following:
In order to receive payment you must submit the following receipts:
Please note that the amount of reimbursement is limited and not all of your expenses incurred in performing retrofit work on your home may be covered or reimbursed.
All photos should be taken with sufficient natural light or light from the flash to show sufficient detail of the structure or work. Include clear photos of the following:
For CRMP-funded program requirements:
FEMA-funded programs requirements:
5 photos of the exterior of the house (see examples here). Photos must be date stamped, taken before the retrofit work begins and taken from the following views:
5 photos of the exterior of the house (see examples here). Photos must be date stamped, taken after the retrofit work begins and taken from the following views:
Digital photos and receipts should be uploaded on the homeowner dashboard. Only electronic uploads through the homeowner dashboard will be accepted. Only documents in JPG or PNG formats can be accepted.
Reimbursement checks will only be processed once your application is complete, all documentation and requested information has been provided to CRMP, and your application has been approved. Once approved, it will take approximately three weeks for you to receive your reimbursement payment.
The homeowner of a retrofit House under the Program will receive an IRS Form 1099, if applicable, reporting the amount of incentive payments as taxable income to the homeowner for federal income tax purposes.
PLEASE NOTE: If requested by EBB, the homeowner must provide a completed IRS Form W-9 showing the homeowner’s social security number or federal taxpayer identification number before the incentive payments can be made.
CRMP is unable to provide legal or tax advice to homeowners or contractors and encourages you to seek appropriate professional advice on the federal tax implications of any incentive payment received for retrofits to your House.
The FEMA-funded program is non-taxable.
Participating Policyholders are advised to review local County Assessor’s or State Board of Equalization’s website regarding any pre-construction requirements concerning the seismic retrofitting construction exclusion from assessment provided by section 74.5 of the California Revenue and Taxation Code.
A building permit is a certificate from the building department authorizing construction on a building or structure within their jurisdiction. According to the California Building Code, no building or structure shall be altered, repaired, or improved unless a separate permit for each building or structure has first been obtained from the building official.
Your local building department may be managed by your city, town or county. For a list of building departments, see the California Contractors State License Board website. Contact your local building department prior to starting work to verify all local requirements.
Permit costs vary. Check with your local building department for costs and other requirements. The cost of the permit is a reimbursable expense (please note that there is a limit on the retrofit incentive payment).
Building departments typically will allow a homeowner or their contractor to take out a permit. Homeowners who intend to act as an owner-builder should check with their building department for specific requirements.
You will need to identify the local building department that is responsible for issuing permits in your location. We recommend that you contact the building department in your jurisdiction for specific building permit requirements prior to commencing with any retrofit work. For a list of building departments, see the California Contractors State License Board website.
The building permit must include the following language under "proposed scope of work": Work is in general accordance with an accepted Standard Plan Set (i.e. Standard Plan Set A or Los Angeles Standard Plan Number One) or Chapter A3 or an engineered solution.
The type and number of inspections required by the building code official may vary from jurisdiction to jurisdiction. The building department will provide information about required inspections when the permit is issued. It is the responsibility of the owner-builder or contractor to schedule inspections with the building department and provide access for the inspector to review the work.
You should verify the requirements for sign off on the building permit with your building code official. Typically the work described in Chapter A3 requires one or more inspections by the building official. Verify the inspection requirements prior to starting the work. Make sure the building permit includes the following language under "proposed scope of work": Work is in general accordance with the California Existing Building Code Appendix Chapter A3.
Some of the retrofit provisions in Chapter A3 may be approved by a building code official without requiring plans or calculations prepared by a design professional (architect or engineer). Homeowners, contractors and design professionals should check with the local building code official to verify local requirements.
We recommend you learn how to protect yourself and what questions you should ask before hiring a contractor. This information is available from the Contractors State License Board here.
In selecting a contractor, the California State License Board recommends that you make sure the contractor has a license, get at least three written bids on the project, ask for personal recommendations, verify the contractor's business location and telephone number, and verify the contractor's workers compensation and commercial general liability insurance coverage.You can search for general contractors with license type A or B in the Contractor Directory on the EBB website.
The California State License Board provides online services that allow homeowners to verify information about contractors, including their license number and business name. The general contractor selected will need to have a license type A or B.
The seismic retrofit work outlined in Chapter A3 can likely be completed by a homeowner with Do-It-Yourself skills. When you undertake work on your home without a licensed contractor you act as an owner-builder. Information about the requirements and risks of acting as an owner-builder may be found on the California State License Board website.
Check with your building department to verify what construction documents (drawings and other specifications) are required to obtain a permit. Some building departments may require a plan showing overall building dimensions and notes indicating where work will be performed. Chapter A3 includes retrofit details that may be referenced on the plan. Some building departments may have standard plan sets that the owner-builder or contractor can use. Please note that any modifications to the details in Chapter A3 must be designed by a registered design professional (architect or engineer).
There are a few "plan sets" available to homeowners and contractors for use as the construction documents for the seismic retrofit of wood frame dwellings. The plan sets include specifications, details, and instructions for the installation of foundation anchors and cripple wall bracing (for walls shorter than 4'-0" tall). These plan sets are intended for use without the services of a design professional (architect or engineer).
You should check with your local building department to see if they have adopted a standard plan set. If so, confirm that your local building department will accept the use of the plan set for a retrofit in accordance with the CEBC Chapter A3.
"Plan Set A" is available for download on the Association of Bay Area Government (ABAG) website. Los Angeles Plan Number One is available to download. If your local building department has not adopted their own plan set, check with them to see if they will allow use of Plan Set A or the LA Plan Number One.
Resources for strapping and bracing your water heater include: Earthquake Country Alliance
Chapter A3 contains specific requirements regarding the condition of the cripple wall wood framing. You or your contractor should inspect wood framing members and check with your local building official to determine if repair or replacement is needed, and if so, whether the assistance of an architect or engineer is required. When preparing your budget or seeking bids from contractors, architects or engineers, be sure to include any repairs or replacements to damaged wood framing members in your retrofits.
Chapter A3 contains specific requirements regarding the condition and strength of your foundation. You or your contractor should inspect if there are cracks in the concrete or masonry foundation and check with your local building official to determine if repair or replacement is needed, and if so, whether the assistance of an architect or engineer is required. When preparing your budget or seeking bids from contractors, architects or engineers, be sure to include any repairs or replacement of concrete or masonry foundation in your retrofits.
Often it is difficult to see the original nails used to connect the first floor to the supporting cripple wall. This is something a design professional or contractor may be able to assist with. If the nails are not visible, consider installation of new framing clips between the top plate of the cripple wall and the blocking or rim joist at the first floor. Chapter A3 includes the required size and spacing for these framing clips.
The requirements of Chapter A3 have some flexibility to accommodate existing conditions. The owner-builder or contractor should verify the length of wall available, and indicate that length for plywood sheathing and bolting on the construction document turned in for the building permit. The building code official is responsible for accepting the final length of sheathing or bolting.
Typically, building inspectors issue a written documentation of items that do not pass inspection. It is the responsibility of the owner-builder or contractor to make revisions and have those revisions re-inspected by the building department. Please note that many building departments charge for re-inspections. Review inspection requirements and fees with your building department prior to starting construction.